Hydroxylic aromatic compounds as additives for rubber-based, composite solid propellants

Abstract

Contaminant metal ions of the transition elements such as copper and iron for example may give rise to serious problems in the curing of polymeric binders for conventional rubber-based solid propellants. These metal ions may accelerate the curing action to such a degree that the potlife of the freshly mixed polymer is reduced. Also, the metal ions may promote oxidative degradation of cured and uncured polymeric systems. These undesirable effects can be prevented by adding to the uncured polymer certain polymer-soluble agents which are capable of forming stable complexes with the undesirable metal ions in which the valence of the metal ion is fixed. These agents are selected from a large group of compounds and compositions comprising certain hydroxy substituted aromatic compositions. The preferred embodiments are pyrogallol, propyl gallate, octyl gallate, decyl gallate, purpurogallin and alizarin.

I claim: 
     
       1. A method for extending the potlife of a curable hydroxy-functional polybutadiene polymeric system which comprises adding to said polymeric system a material selected from the group consisting of: ##STR8## wherein R is a radical which does not interfere with the effectiveness of said material in producing potlife extension. 
     
     
       2. The method of claim 1 wherein said material is selected from the group consisting of pyrogallol, purpurogallin, alizarin, propyl gallate, octyl gallate, decyl gallate, methyl gallate, ethyl gallate, pentaerythrityl gallate, polybutadieneyl gallate, gallamide, gallomine blue, gallocyanine, the acetyl ferrocene condensation product of pyrogallol, the acetyl ferrocene condensation product of purpurogallin, gallotannin, extract of nutgall, extract of oakgall, extract of tanbark, m-galloylgallic acid, 1,2,3 trihydroxy-5-butyl benzene, 3,4,5,3',4',5' hexahydroxydiphenylmethane, anthragallol, purpurin, flavopurin, rufigallic acid and gallacetophenone. 
     
     
       3. The method of claim 1 wherein said material is pyrogallol. 
     
     
       4. The method of claim 1 wherein said material is purpurogallin. 
     
     
       5. The method of claim 1 wherein said material is an alkyl gallate in which the alkyl group has from 1-10 carbon atoms. 
     
     
       6. The method of claim 1 wherein said material is alizarin. 
     
     
       7. The method of claims 1; 2; 3; 4; 5, or 6 wherein said polymeric system has a particulate oxidizing agent dispersed therethrough. 
     
     
       8. (a) A curable polymeric system comprising a hydroxy-functional polybutadiene; and (b) A material selected from the group consisting of: ##STR9## wherein R is a radical which does not interfere with the curability of the polymeric system.   
     
     
       9. The composition of claim 8 wherein said material is selected from the group consisting of pyrogallol, purpurogallin, alizarin, propyl gallate, octyl gallate, decyl gallate, methyl gallate, ethyl gallate, pentaerythrityl gallate, polybutadieneyl gallate, gallamide, gallomine blue, gallocyanine, the acetyl ferrocene condensation product of pyrogallol, the acetyl ferrocene condensation product of purpurogallin, gallotannin, extract of nutgall, extract of oakgall, extract of tanbark, m-galloylgallic acid, 1,2,3 trihydroxy-5-butyl benzene, 3,4,5,3',4',5' hexahydroxydiphenylmethane, anthragallol, purpurin flavopurin, rufigallic acid and gallacetophenone. 
     
     
       10. The composition of claim 8 wherein said material is pyrogallol. 
     
     
       11. The composition of claim 8 wherein said material is purpurogallin. 
     
     
       12. The composition of claim 8 wherein said material is an alkyl gallate in which the alkyl group is from 1-10 carbon atoms. 
     
     
       13. The composition of claim 8 wherein said material is alizarin. 
     
     
       14. The composition of claims 8; 9; 10; 11; 12, or 13 further comprising a curing agent for said polymeric system. 
     
     
       15. The composition of claim 14 further comprising a solid particulate oxidizing agent dispersed therethrough. 
     
     
       16. The composition produced upon completion of the curing reaction of the composition of claim 15.